Lightroom Classic version 9.4 - cannot import videos

I updated from Lightroom Classic 9.3 to 9.4 and could not import my videos (mp4 and Apple format taken from my iphone).  It keeps saying "Preview not available" in the import page for all videos.  When I changed the version back to 9.3, there is no problem with importing the same videos.  What is the problem and how do I resolve it?  Thanks.